Expandable Networks for Emergency Response Communications

HSMM

High Speed Multi Media (HSMM) is often referred to as being the Hinternet (Ham Internet), as it is primarily used under FCC Rules & Regulations Part 97. Under Part 97 commercial off-the-shelf equipment can be used at higher power and higher gain than the more common Part 15 802.11a/b/g operations.

The primary purpose for HSMM and Hinternet is to augment emergency communications via long range high speed wireless data networks that can handle voice, data and video communications. HSMM can also be used in the day-to-day aspects of Amateur Radio Communications.

The Fit

With the rapid expansion of Asterisk PBX into the relm of radio communications the added flexibility of having a wireless linking system has also expanded.

It is now possible to have a network of repeaters and link stations that never touch a standard public switched telephone network, yet at the same time this network of repeaters and link stations has all the standard features one will expect to find with any telephone system.

By integrating HSMM along with Asterisk PBX a truly transportable network can be delivered to any location where communications is needed, with voice, data and video all being available to the agencies and organizations being supported.

What is needed to initialize HSMM network?

Basic Off-The-Shelf equipment will work with HSMM, one thing to remember is to find equipment that have external antenna jacks available (one of the most common type of antenna connectors in use is R-SMA).

The Linksys WRT54G is one gateway that is mentioned as a being a good choice because of its expandibility.

Consider a high-gain parabolic dish antenna for point-to-point links

When possible mount all the RF equipment as close to the antenna and use POE (Power over Ethernet) to limit cable signal loss.

HSMM 802.11(a),(b),(g) under FCC Part 97.311

802.11(a)

12 Channels Non-Overlapping

5.650 – 5.925 GHz

OFDM

1500 W PEP

802.11(b)

8 Channels Overlapping

2.390 – 2.450 GHz

DSSS

10 W PEP (1)

802.11(g)

8 Channels Overlapping

2.390 – 2.417 GHz

OFDM

1500 W PEP

802.11(n)

8 Channels Overlapping

2.390 – 2.417 GHz

OFDM

1500 W PEP

OFDM : Orthogonal Frequency Division Multiplexing

DSSS : Direct Sequence Spread Spectrum

(1) per FCC Part 97.313(j) pending publication in the Federal Register (4MAR 2011)
Note: 802.11(a) & 802.11(g) OFDM is not defined as being spread spectrum see FCC-01-158A1.pdf